An important goal of drug abuse research is to detect and characterize changes in the biochemistry of the nervous system on upon exposure to drugs of abuse, and to relate these changes to higher neuronal functions in normal and pathological conditions. Amongst numerous signaling molecules, intercellular signaling peptides (ISPs) are a dramatic measurement challenge;there are literally hundreds of peptides expressed in biological systems, many of which are only physiologically active when posttranslationally modified. The proposed research both develops and implements matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) based technologies for the discovery and characterization of ISPs, including determination of their chemical form and spatial localization in the mammalian nervous system. The overall strategy is to develop new technologies and sampling protocols to detect and identify new ISPs in very small biological samples, including individual freshly prepared or cultured single mammalian cells, small groups of cells, and those released from spatially restricted regions of the nervous system. These technologies promise to uncover hundreds of potential ISPs that will be filtered for functional relevance by studies designed to: (A) find peptides with specific post- translational modifications (e.g., amidation);(B) determine the peptides that undergo long- distance transport in the nervous system;(C) discover which peptides are released in an activity-dependent manner. This technology development ideally matches the cutting-edge basic research award solicitation. By developing powerful new proteomics-based technologies to answer questions about the most complex and elusive set of neuromodulators, the neuropeptides, basic insight into the effects of drugs of abuse on the CNS will be gained.